Fine-grained and fair identity authentication scheme for mobile networks based on blockchain

With the popularity of the internet, users hope to better protect their privacy while obtaining network services. However, in the traditional centralized authentication scheme, identity information such as the user's private key is generated, stored, and managed by the network operator. Users can't control their identity information, which will lead to a great threat to the privacy of users. Based on redactable blockchain, we propose a fine-grained and fair identity authentication scheme for mobile networks. In our proposed scheme, the user's identity information is generated and controlled by the users. We first propose a notion of score chameleon hash (SCH), which can delete or update the information of illegal users so as to dynamically update the status of users and provide users with more fine-grained and fair services. We propose another notion of self-updating secret sharing (SUSS), which allows users to update the trapdoor and the corresponding hash key after redacting the blockchain without requiring trusted authority to redistribute the trapdoor. Experimental results show that, compared with the immutable blockchain Bit-coin, the redactable blockchain in our identity authentication scheme provides users with fine-grained and fair redacting functions, and can be adopted with a small additional overhead.